US11124470B2 - Systems and methods of producing methyl tertiary butyl ether and propylene - Google Patents

Abstract

A method of producing methyl tertiary butyl ether (MTBE) and propylene is disclosed. The method involves the use of a crude C4 stream and the integration of a MTBE synthesis process and a cracking process. The method may include processing a byproduct stream from an MTBE synthesis unit to produce high purity olefin streams for an olefins conversion technology unit.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase application under 35 U.S.C. § 371 of International Application No. PCT/IB2018/052203 filed Mar. 29, 2018, which claims priority to U.S. Provisional Patent Application No. 62/480,687 filed Apr. 3, 2017. The entire contents of each of the above-referenced disclosures is specifically incorporated by reference herein without disclaimer.

FIELD OF INVENTION

The present invention generally relates to the production of methyl tertiary butyl ether (MTBE) and propylene. Specifically the present invention relates to the utilization of crude C₄streams in the production of MTBE and propylene.

BACKGROUND OF THE INVENTION

MTBE is used as a gasoline blending component. Typically, MTBE may be made by reacting isobutylene with methanol. The isobutylene for the reaction is usually obtained from a crude C₄stream. A crude C₄stream is a byproduct stream produced in a cracking process to produce olefins. The crude C₄stream is usually obtained from the steam cracking of hydrocarbons to produce ethylene. Typically, materials that make up the crude C₄stream have similar boiling points; thus extracting any one of the various components of the crude C₄stream can be difficult and expensive.

Propylene serves as a building block for other petrochemical products and may be made by different processes. One of those processes, olefins conversion technology (OCT), involve metathesis and isomerization of hydrocarbons to form the propylene. Another of the processes involve steam cracking larger hydrocarbons to form the propylene. The steam cracking process, in addition to producing propylene, may produce n-butane and isobutane, which are both usually recycled to the transfer hydrogenation unit (THU) of the steam cracker.

Conventionally, the MTBE production process and the OCT process are not integrated with the steam cracking process. Moreover, the stream from the steam cracker that includes the n-butane and isobutane is not pure enough to be utilized in MTBE production.

BRIEF SUMMARY OF THE INVENTION

A method has been discovered in which purified 1-butene and 2-butene streams can be obtained from a stream that emanates from a steam cracker and that includes primarily normal butane (n-butane) and isobutane collectively. The n-butane and isobutane are inert in certain processes, such as butadiene production process, MTBE production process, 1-butene production process, and OCT process (metathesis). Accommodating the n-butane and isobutane volumes from the steam cracker in these processes, when they do not help in achieving the objective of those processes, would have a direct effect in the operational efficiency, technical efficiency, and the capital expenditure required for these processes. Thus, in embodiments of the invention, the materials that are inert to the processes are removed from the streams entering one or more of those processes. In this way, capital expenditure for the equipment and the efficiency of the processes are kept at optimal levels.

Embodiments of the invention include a method of producing methyl tertiary butyl ether (MTBE) and propylene. The method may include flowing a crude C₄stream comprising butadiene, isobutylene, 2-butene, 1-butene, acetylene, isobutane, and n-butane to a selective hydrogenation unit and hydrogenating the butadiene in the selective hydrogenation unit to form additional 1-butene and additional 2-butene. The additional 1-butene, the additional 2-butene and unreacted material of the crude C₄stream are included in effluent of the selective hydrogenation unit. The method may further include flowing the effluent of the selective hydrogenation unit to a MTBE synthesis unit and reacting, in the MTBE synthesis unit, the isobutylene from the crude C₄stream with methanol (MeOH) to produce the MTBE. The method may further include flowing, from the MTBE synthesis unit, a byproduct stream comprising 1-butene, isobutane, 2-butene, and n-butane to a processing unit, and processing, in the processing unit, the byproduct stream to produce a first stream comprising primarily 1-butene and a second stream comprising primarily 2-butene. The method may further include flowing the second stream comprising primarily 2-butene to an olefins conversion technology unit and reacting the 2-butene with ethylene to produce propylene.

Embodiments of the invention include a method of producing methyl tertiary butyl ether (MTBE) and propylene. The method may include flowing a crude C₄stream comprising butadiene, isobutylene, 2-butene, 1-butene, acetylene, isobutane, and n-butane to a selective hydrogenation unit and hydrogenating the butadiene in the selective hydrogenation unit to form additional 1-butene and additional 2-butene. The additional 1-butene, the additional 2-butene and unreacted material of the crude C₄stream are included in effluent of the selective hydrogenation unit. The method may further include flowing the effluent of the selective hydrogenation unit to a MTBE synthesis unit and reacting, in the MTBE synthesis unit, the isobutylene from the crude C₄stream with methanol (MeOH) to produce the MTBE. The method may further include flowing, from the MTBE synthesis unit, a byproduct stream comprising 1-butene, isobutane, 2-butene, and n-butane to a processing unit. Further, the method may include distilling, in a distillation column of the processing unit, the byproduct stream to form a first intermediate stream comprising primarily 1-butene and isobutane and a second intermediate stream comprising primarily 2-butene and n-butane. The method may then include hydro-isomerizing of the 1-butene in the first intermediate stream to produce a stream comprising primarily 2-butene and isobutane and separating the stream comprising primarily 2-butene and isobutane into a stream comprising primarily 2-butene and a stream comprising primarily isobutane. The method may further include isomerization of the 2-butene of the second intermediate stream to form a stream comprising primarily 1-butene and n-butane and separating the stream comprising primarily 1-butene and n-butane to form a stream comprising primarily 1-butene and a stream comprising primarily n-butane. The method may include flowing the stream comprising primarily 2-butene and the stream comprising primarily 1-butene to an olefins conversion technology unit, converting 1-butene of the stream comprising primarily 1-butene to 2-butene in the olefins conversion technology unit, and reacting the 2-butene in the olefins conversion technology unit with ethylene to produce propylene.

The following includes definitions of various terms and phrases used throughout this specification.

The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

The terms “wt. %”, “vol. %” or “mol. %” refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 moles of component in 100 moles of the material is 10 mol. % of component.

The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and/or the specification, includes any measurable decrease or complete inhibition to achieve a desired result.

The term “effective,” as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

The use of the words “a” or “an” when used in conjunction with the term “comprising,” “including,” “containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.”

The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

The process of the present invention can “comprise,” “consist essentially of,” or “consist of” particular ingredients, components, compositions, etc., disclosed throughout the specification.

In the context of the present invention at least the nineteen preferred embodiments are described.Embodiment 1 is a method of producing methyl tertiary butyl ether (MTBE) and propylene. The method includes the steps of flowing a crude C4 stream containing butadiene, isobutylene, 2-butene, 1-butene, acetylene, isobutane, and n-butane to a selective hydrogenation unit; hydrogenating the butadiene in the selective hydrogenation unit to form additional 1-butene and additional 2-butene, wherein the additional 1-butene and the additional 2-butene and unreacted material of the crude C4 stream is included in effluent of the selective hydrogenation unit; flowing the effluent of the selective hydrogenation unit to a MTBE synthesis unit; reacting, in the MTBE synthesis unit, the isobutylene from the crude C4 stream with methanol (MeOH) to produce the MTBE, flowing, from the MTBE synthesis unit, a byproduct stream containing 1-butene, isobutane, 2-butene, and n-butane to a processing unit; processing, in the processing unit, the byproduct stream to produce a first stream containing primarily 1-butene and a second stream containing primarily 2-butene; flowing the second stream containing primarily 2-butene to an olefins conversion technology unit; and reacting the 2-butene with ethylene to produce propylene.Embodiment 2 is the method ofembodiment1 further including the step of hydrogenating the butadiene in the selective hydrogenation unit to form additional isobutane and additional n-butane. Embodiment 3 is the method of any ofembodiments 1 and 2, wherein processing, in the processing unit includes the step of distilling, in a distillation column of the processing unit, the byproduct stream to form a first intermediate stream containing primarily 1-butene and isobutane, collectively, and a second intermediate stream containing primarily 2-butene and n-butane, collectively. Embodiment 4 is the method of embodiment 3, further including the step of processing the first intermediate stream to produce a stream containing primarily 2-butene and a stream containing primarily isobutane. Embodiment 5 is the method of embodiment 4, wherein the processing of the first intermediate stream includes the steps of hydro-isomerizing of the 1-butene in the first intermediate stream to produce a stream containing primarily 2-butene and isobutane, collectively; and separating the stream containing primarily 2-butene and isobutane into the stream containing primarily 2-butene and the stream containing primarily isobutane. Embodiment 6 is the method of embodiment 5, further including the step of flowing the stream containing primarily 2-butene to the olefins conversion technology unit. Embodiment 7 is the method of any of embodiments 3 to 6, further including the step of processing the second intermediate stream to form a stream containing primarily 1-butene and a stream containing primarily n-butane. Embodiment 8 is the method of embodiment 7, wherein the processing the second intermediate stream includes the steps of isomerizing the 2-butene of the second intermediate stream to form a stream containing primarily 1-butene and n-butane, collectively; and separating the stream containing primarily 1-butene and n-butane to form the stream containing primarily 1-butene and the stream containing primarily n-butane. Embodiment 9 is the method of embodiment 8, further including the step of flowing the stream containing primarily 1-butene to the olefins conversion technology unit; converting 1-butene of the stream containing primarily 1-butene to 2-butene in the olefins conversion technology unit.Embodiment 10 is the method of any ofembodiments 1 to 9, wherein the acetylene in the crude C4 stream contains ethyl acetylene and vinyl acetylene. Embodiment 11 is the method of any ofembodiments 1 to 10, wherein the butadiene contains 1,3-butadiene and 1,2-butadiene. Embodiment 12 is the method of any ofembodiments 1 to 11, wherein the 2-butene contains cis-2-butene and trans-2-butene. Embodiment 13 is the method of any ofembodiments 1 to 12, wherein the MTBE synthesis unit contains a separation unit. Embodiment 14 is the method of any ofembodiments 1 to 13, wherein the crude C4 stream is at least a portion of effluent from a fluid catalytic cracking unit or steam cracking unit. Embodiment 15 is the method of embodiment 14 wherein the stream containing primarily isobutane is used as feedstock for a selection from the group consisting of: (1) a dehydrogenation unit of the MTBE synthesis unit to produce additional isobutylene and (2) a transfer hydrogenation unit (THU) of the steam cracking unit to produce ethylene and propylene. Embodiment 16 is the method of embodiment 15, wherein the additional isobutylene is used to produce MTBE. Embodiment 17 is the method of embodiment 14, wherein the stream containing primarily n-butane is used as feedstock for a selection from the list consisting of: (1) an isomerization unit of the MTBE synthesis unit to produce more isobutane, (2) a transfer hydrogenation unit (THU) of the steam cracking unit to produce ethylene and propylene. Embodiment 18 is the method of embodiment 17, wherein the more isobutane is dehydrogenated to produce more isobutylene and the more isobutylene is used to produce MTBE. Embodiment 19 is the method of any ofembodiments 2 to 18, wherein conversion of butadiene to other hydrocarbons in the selective hydrogenation unit is in a range of 88 wt. % to 92 wt. %.

Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a system for producing methyl tertiary butyl ether (MTBE) and propylene, according to embodiments of the invention; and

FIG. 2 shows a method for producing methyl tertiary butyl ether (MTBE) and propylene, according to embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

A method has been discovered in which purified 1-butene and 2-butene streams can be obtained from a stream that emanates from a steam cracker and that includes primarily normal butane (n-butane) and isobutane, collectively. Embodiments of the invention include a method of producing methyl tertiary butyl ether (MTBE) and propylene. The method may first involve converting at least some of the butadiene to 1-butene and 2-butene. This may be done by flowing a crude C₄stream comprising butadiene, isobutylene, 2-butene, 1-butene, acetylene, isobutane, and n-butane to a selective hydrogenation unit (which comprises a hydrogenation reactor) and hydrogenating the butadiene in the selective hydrogenation unit to form additional 1-butene and additional 2-butene. The additional 1-butene and the additional 2-butene and unreacted material of the crude C₄stream are included in effluent of the selective hydrogenation unit. The method may further include removing most of the isobutylene by using it to produce MTBE. This may be done by flowing the effluent of the selective hydrogenation unit to a MTBE synthesis unit (which comprises an MTBE synthesis reactor) and reacting, in the MTBE synthesis unit, the isobutylene from the crude C₄stream with methanol (MeOH) to produce the MTBE. The method may further include flowing, from the MTBE synthesis unit, a byproduct stream comprising 1-butene, isobutane, 2-butene, and n-butane to a processing unit.

Further, the method may include separating the byproduct stream into different streams. This separating may involve distilling, in a distillation column of the processing unit, the byproduct stream to form a first intermediate stream comprising primarily 1-butene and isobutane, collectively, and a second intermediate stream comprising primarily 2-butene and n-butane, collectively. The first stream and the second stream may undergo separate processes, based on the composition of these streams, to produce feedstock for an OTC unit that produces propylene. The method may then include hydro-isomerizing of the 1-butene in the first intermediate stream to produce a stream comprising primarily 2-butene and isobutane, collectively, and separating the stream comprising primarily 2-butene and isobutane into a stream comprising primarily 2-butene and a stream comprising primarily isobutane. The method may further include isomerization of the 2-butene of the second intermediate stream to form a stream comprising primarily 1-butene and n-butane, collectively, and separating the stream comprising primarily 1-butene and n-butane to form a stream comprising primarily 1-butene and a stream comprising primarily n-butane. The method may include flowing the stream comprising primarily 2-butene and the stream comprising primarily 1-butene to an olefins conversion technology unit, converting 1-butene of the stream comprising primarily 1-butene to 2-butene in the olefins conversion technology unit, and reacting the 2-butene in the olefins conversion technology unit with ethylene to produce propylene.

FIG. 1 showssystem10 for producing methyl tertiary butyl ether (MTBE) and propylene, according to embodiments of the invention.FIG. 2shows method20 for producing methyl tertiary butyl ether (MTBE) and propylene, according to embodiments of the invention.Method20 may be implemented usingsystem10.

Method20 may begin atblock200, which involves flowing crude C₄stream100, comprising butadiene, isobutylene, 2-butene, 1-butene, acetylene, isobutane, and n-butane toselective hydrogenation unit101. In embodiments of the invention, crude C₄stream100 is at least a portion of effluent from a fluid catalytic cracking unit or steam cracking unit. In embodiments of the invention, crude C₄stream100 comprises 0.01 to 50 wt. % butadiene, 0.01 to 50 wt. % isobutylene, 0.01 to 15 wt. % 2-butene, 0.01 to 15 wt. % 1-butene, 0.01 to 0.2 wt. % acetylene, 0.01 to 25 wt. % isobutane, and 0.01 to 50 wt. % n-butane. In embodiments of the invention, the acetylene in crude C₄stream100 comprises ethyl acetylene and vinyl acetylene. Further, in embodiments of the invention, the butadiene in crude C₄stream100 may comprise 1,3-butadiene and 1,2-butadiene. The 2-butene in crude C₄stream100, in embodiments of the invention, comprises cis-2-butene and trans-2-butene.

Block201 may involve selectively hydrogenating the butadiene inselective hydrogenation unit101 to form additional 1-butene and additional 2-butene. In embodiments of the invention, the reaction conditions inselective hydrogenation unit101 include a temperature in the range 40 to 120° C., a pressure in the range 5 to 50 bar, and a gas hourly space velocity in the range 0.1 to 30 hr⁻¹. The additional 1-butene, the additional 2-butene, and unreacted material of crude C₄stream100, according to embodiments of the invention, are included ineffluent102 fromselective hydrogenation unit101.Block201 may also involve, in embodiments of the invention, selectively hydrogenating the butadiene inselective hydrogenation unit101 to form additional isobutane and additional n-butane. In embodiments of the invention, the conversion rate of the butadiene to the additional 1-butene and the additional 2-butene is 88 wt. % to 92 wt. %. In embodiments of the invention,effluent102 comprises 0.001 to 0.01 wt. % butadiene, 0.01 to 15 wt. % isobutylene, 0.01 to 50 wt. % 2-butene, 0.01 to 50 wt. % 1-butene, 0.0001 to 0.01 wt. % acetylene, 0.01 to 50 wt. % isobutane, and 0.01 to 50 wt. % n-butane.

Atblock202,effluent102 fromselective hydrogenation unit101 is flowed toMTBE synthesis unit103. InMTBE synthesis unit103, block203 is carried out, which involves reacting isobutylene from effluent102 (and originally from the crude C₄stream100) with methanol (MeOH)104 to produce theMTBE105.

In embodiments of the invention,MTBE synthesis unit103 includes a separation unit for separatingMTBE105 and byproduct stream106.Block204 involves flowing byproduct stream106, which may comprise 1-butene, isobutane, 2-butene, and n-butane, fromMTBE synthesis unit103 toprocessing unit107. In embodiments of the invention, byproduct stream106 comprises 0.01 to 45 wt. % 2-butene, 0.01 to 45 wt. % 1-butene, 0.01 to 50 wt. % isobutane, and 0.01 to 50 wt. % n-butane.

Processing unit107, as a whole, may be adapted to carry outblock205, which involves processing byproduct stream106 to produce 1-butene stream108 (a high purity stream), comprising primarily 1-butene, and 2-butene stream109 (a high purity stream), comprising primarily 2-butene.Process unit107 may include various processing components for carrying out the processing ofblock204.

For example,method20 may include, at block205-1, distilling, in distillation column110 (of processing unit107) byproduct stream106 to formstream111 comprising primarily 1-butene and isobutane, collectively, and stream112 comprising primarily 2-butene and n-butane, collectively. In embodiments of the invention,stream111 comprises 0.01 to 70 wt. % 1-butene and 0 to 50 wt. % isobutane. In embodiments of the invention,stream112 comprises 0.01 to 70 wt. % 2-butene and 0.01 to 50 wt. % isobutane.

At block205-2,stream111 may be processed, inprocessing subunit121 to produce 2-butene stream109, which comprises primarily 2-butene and stream119 (a high purity stream) that comprises primarily isobutane. In embodiments of the invention,stream109 comprises 90 to 99.9 wt. % 2-butene. In embodiments of the invention,stream119 comprises 90 to 99.9 wt. % isobutane.

Processing subunit121 may comprise hydro-isomerization unit113 andseparation unit117. Hydro-isomerization unit113 may be used to implement block205-2A, which involves hydro-isomerizing of 1-butene instream111 to produce stream115, which comprises primarily 2-butene and isobutane, collectively. In embodiments of the invention, the reaction conditions in hydro-isomerization unit113 include a temperature in therange 110 to 300° C., a pressure in the range 15 to 30 bar, and a gas hourly space velocity in the range 4 to 8 hr⁻¹.Separation unit117 may be used to carry out block205-2B, which involves separating stream115 (comprising primarily 2-butene and isobutane) into 2-butene stream109 (comprising primarily 2-butene) and stream119 (comprising primarily isobutane). In embodiments of the invention,separation unit117 comprises one or more distillation columns. In embodiments of the invention, stream115 comprises 0.01 to 70 wt. % 2-butene and 0.01 to 50 wt. % isobutane.

At block205-3,stream112 may be processed, inprocessing subunit122 to produce 1-butene stream108, which comprises primarily 1-butene andstream120, a high purity stream that comprises primarily n-butane. In embodiments of the invention,stream108 comprises 90 to 99.9 wt. % 1-butene. In embodiments of the invention,stream120 comprises 90 to 99.9 wt. % n-butane.

Processing subunit122 may comprise butene isomerization unit (BIU)114 (which comprises an isomerization reactor) andseparation unit118. In embodiments of the invention, the reaction conditions inbutene isomerization unit114 include a temperature in the range 50 to 750° C., a pressure in the range 0.5 to 50 bar, and a weight hourly space velocity in therange 1 to 10 hr⁻¹.Butene isomerization unit114 may be used to implement block205-3A, which involves isomerizing the 2-butene of stream112 (comprising primarily 2-butene and n-butane, collectively) to form 1-butene of stream116 (comprising primarily 1-butene and n-butane, collectively).Butene isomerization unit114 may include three reactor stages. The first two reactor stages may contain the same catalyst. The third stage reactor may contain a different catalyst.

Separation unit118 may be used to carry out block205-3B, which involves separating stream116 (comprising primarily 1-butene and n-butane, collectively) into 1-butene stream108 (comprising primarily 1-butene) and stream120 (comprising primarily n-butane). In embodiments of the invention,separation unit118 comprises one or more distillation columns. In embodiments of the invention,stream116 comprises 0.01 to 70 wt. % 1-butene and 0.01 to 50 wt. % n-butane.

Block206 ofmethod20 involves flowing 2-butene stream109 to olefinsconversion technology unit123. Likewise, block207 involves flowing 1-butene stream108 to olefinsconversion technology unit123. At olefinsconversion technology unit123, block208 involves converting 1-butene of 1-butene stream108 to 2-butene. Atblock208, 2-butene in olefins conversion technology unit123 (e.g., 2-butene from 2-butene stream109 and/or 2-butene converted from 1-butene stream108) is reacted with ethylene124 to producepropylene131.

In embodiments of the invention, olefins (e.g., 1-butene and/or 2-butene) may be separated fromeffluent102 and recycled to steam cracking (cracker)unit126.

In embodiments of the invention, stream119 (comprising primarily isobutane) from processing subunit121 (hydro-isomerization unit113) may be used as feedstock for a selection from the following list: a dehydrogenation unit ofMTBE synthesis unit103 and a transfer hydrogenation unit (THU) ofsteam cracking unit126 to produce ethylene and propylene. When isobutane is dehydrogenated in the isobutane dehydrogenation unit ofMTBE synthesis unit103, this process provides an increase in isobutylene available for reaction to produce MTBE.

Likewise, in embodiments of the invention, stream120 (comprising primarily n-butane) from processing subunit122 (butene isomerization unit114) may be used as feedstock for a selection from the following list: an isomerization unit ofMTBE synthesis unit103 and a transfer hydrogenation unit (THU) ofsteam cracking unit126 to produce ethylene and propylene. The isomerization ofMTBE synthesis unit103 isomerizes the n-butane to form isobutane; this process provides an increase in isobutane, which in turn can be used as feed to the dehydrogenation unit to form isobutylene and thereby make more isobutylene available for reaction to produce MTBE.

The additional production of MTBE resulting from the isomerizing of the additional n-butane frombutene isomerization unit114 fed to the isomerizing unit and the additional isobutane from hydro-isomerizingunit113 fed to the dehydrogenating unit, as described above, can maximize MTBE production from the steam cracker recycle stream and integrate two different systems/processes, namely MTBE system/process and steam cracker system/process.

In embodiments of the invention,purge stream127 is combined withstream119, and stream120 to form combinedstream128, which may be fed to steam crackingunit126.Steam cracking unit126 cracks hydrocarbons of the streams it receives to produceolefins130. In embodiments of the invention,stream129 is recycled fromsteam cracking unit126 and fed toselective hydrogenation unit101 along with crude C₄stream100.

In view of the processing described with respect toprocessing unit107, the conversion of butadiene to 1-butene and 2-butene, previously described, can increase substantially the available 2-butene stream available for olefinsconversion technology unit123 and thereby maximize the amount of propylene produced.

Although embodiments of the present invention have been described with reference to blocks ofFIG. 2, it should be appreciated that operation of the present invention is not limited to the particular blocks and/or the particular order of the blocks illustrated inFIG. 2. Accordingly, embodiments of the invention may provide functionality as described herein using various blocks in a sequence different than that ofFIG. 2.

Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (20)

The invention claimed is:

1. A method of producing methyl tertiary butyl ether (MTBE) and propylene, the method comprising:

flowing a crude C₄stream comprising butadiene, isobutylene, 2-butene, 1-butene, acetylene, isobutane, and n-butane to a selective hydrogenation unit;

hydrogenating the butadiene in the selective hydrogenation unit to form additional 1-butene and additional 2-butene, wherein the additional 1-butene and the additional 2-butene and unreacted material of the crude C₄stream is included in effluent of the selective hydrogenation unit;

flowing the effluent of the selective hydrogenation unit to a MTBE synthesis unit;

reacting, in the MTBE synthesis unit, the isobutylene from the crude C₄stream with methanol (MeOH) to produce the MTBE,

flowing, from the MTBE synthesis unit, a byproduct stream comprising 1-butene, isobutane, 2-butene, and n-butane to a processing unit;

processing, in the processing unit, the byproduct stream to produce a first stream comprising primarily 1-butene and a second stream comprising primarily 2-butene;

flowing the second stream comprising primarily 2-butene to an olefins conversion technology unit; and

reacting the 2-butene with ethylene to produce propylene.

2. The method ofclaim 1 further comprising:

hydrogenating the butadiene in the selective hydrogenation unit to form additional isobutane and additional n-butane; and

wherein conversion of butadiene to other hydrocarbons in the selective hydrogenation unit is in a range of 88 wt. % to 92 wt. %.

3. The method ofclaim 1, wherein processing, in the processing unit, comprises:

distilling, in a distillation column of the processing unit, the byproduct stream to form a first intermediate stream comprising primarily 1-butene and isobutane, collectively, and a second intermediate stream comprising primarily 2-butene and n-butane, collectively.

4. The method ofclaim 3, further comprising:

processing the first intermediate stream to produce a stream comprising primarily 2-butene and a stream comprising primarily isobutane.

5. The method ofclaim 4, wherein the processing of the first intermediate stream comprises:

hydro-isomerizing, in a hydro-isomerization unit, of the 1-butene in the first intermediate stream to produce a stream comprising primarily 2-butene and isobutane, collectively; and

separating the stream comprising primarily 2-butene and isobutane into the stream comprising primarily 2-butene and the stream comprising primarily isobutane.

6. The method ofclaim 5, further comprising:

flowing the stream comprising primarily 2-butene to the olefins conversion technology unit.

7. The method ofclaim 3, further comprising:

processing the second intermediate stream to form a stream comprising primarily 1-butene and a stream comprising primarily n-butane.

8. The method ofclaim 7, wherein the processing the second intermediate stream comprises:

isomerizing the 2-butene of the second intermediate stream to form a stream comprising primarily 1-butene and n-butane, collectively; and

separating the stream comprising primarily 1-butene and n-butane to form the stream comprising primarily 1-butene and the stream comprising primarily n-butane.

9. The method ofclaim 8, further comprising:

flowing the stream comprising primarily 1-butene to the olefins conversion technology unit;

converting 1-butene of the stream comprising primarily 1-butene to 2-butene in the olefins conversion technology unit.

10. The method ofclaim 1, wherein the acetylene in the crude C4 stream comprises ethyl acetylene and vinyl acetylene.

11. The method ofclaim 1, wherein the butadiene comprises 1,3-butadiene and 1,2-butadiene.

12. The method ofclaim 5, wherein reaction conditions in hydro-isomerization unit113 include a temperature in the range 110 to 300° C., a pressure in the range 15 to 30 bar, and a gas hourly space velocity in the range 4 to 8 hr¹.

13. The method ofclaim 8, wherein the stream comprising primarily 1-butene comprises 90 to 99.9 wt. % 1-butene.

14. The method ofclaim 1, wherein the crude C4 stream is at least a portion of effluent from a fluid catalytic cracking unit or steam cracking unit.

15. The method ofclaim 14 wherein the stream comprising primarily isobutane is used as feedstock for a selection from the list consisting of: (1) a dehydrogenation unit of the MTBE synthesis unit to produce additional isobutylene and (2) a transfer hydrogenation unit (THU) of the steam cracking unit to produce ethylene and propylene.

16. The method ofclaim 15, wherein the additional isobutylene is used to produce MTBE.

17. The method ofclaim 14, wherein the stream comprising primarily n-butane is used as feedstock for a selection from the list consisting of: (1) an isomerization unit of the MTBE synthesis unit to produce more isobutane, (2) a transfer hydrogenation unit (THU) of the steam cracking unit to produce ethylene and propylene.

18. The method ofclaim 13, wherein the stream comprising primarily n-butane comprises 90 to 99.9 wt. % n-butane.

19. The method ofclaim 5, wherein a purge stream is combined with the stream comprising primarily isobutane and the stream comprising primarily n-butane to form combined stream, which may be fed to a steam cracking unit.

20. A method of producing methyl tertiary butyl ether (MTBE) and propylene, the method consisting of the steps of:

flowing a crude C₄stream comprising butadiene, isobutylene, 2-butene, 1-butene, acetylene, isobutane, and n-butane to a selective hydrogenation unit;

hydrogenating the butadiene in the selective hydrogenation unit to form additional 1-butene and additional 2-butene, wherein the additional 1-butene and the additional 2-butene and unreacted material of the crude C₄stream is included in effluent of the selective hydrogenation unit;

flowing the effluent of the selective hydrogenation unit to a MTBE synthesis unit;

reacting, in the MTBE synthesis unit, the isobutylene from the crude C₄stream with methanol (MeOH) to produce the MTBE,

flowing, from the MTBE synthesis unit, a byproduct stream comprising 1-butene, isobutane, 2-butene, and n-butane to a processing unit;

processing, in the processing unit, the byproduct stream to produce a first stream comprising primarily 1-butene and a second stream comprising primarily 2-butene;

flowing the second stream comprising primarily 2-butene to an olefins conversion technology unit; and

reacting the 2-butene with ethylene to produce propylene.

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